. B. pertussis is an important pathogen of children and increasingly also of adults worldwide. The substantial beneficial health impact of the diphtheria-pertussis-tetanus vaccine is achieved at the cost of the toxicity of the controversial pertussis component. As many steps in the pathogenicity of whooping cough are still undefined, rational design of pertussis vaccine improvements is difficult. However, since the disease is entirely non-invasive, understanding of the biology of the adherence interactions between the bacteria and host cell surfaces is of major importance to efforts to interrupt disease. This proposal addresses the mechanisms of two such interactions important in vivo: the specific adherence of virulent B. pertussis to human cilia and macrophages. Two antigenic bacterial surface proteins act as adhesion, each with independent binding regions for human ciliated cells and macrophages. In this program the binding regions will be identified, cloned and subjected to site directed mutogenesis to determine how these adhesion interact with the purified human receptors (the appropriate targets for exclusively human infections). The importance of these epitopes to future subcomponent recombinant pertussis vaccine will be assayed by raising antibodies against adhesive epitopes and testing for the ability to interrupt adherence to human cells in-vitro and in an animal model. Interest in the detailed study of these adhesion is heightened from a biologic view point by their peculiar features of toxicity, non-fimbrial structure, and surprising eukarotyic features of large size, multiple binding sites, and RGD adhesive triplet motifs with integring binding properties. The peptidoglycan of B. pertussis contributes to virulence in that cell wall turnover releases the toxic metabolite, tracheal cytotoxins; which specifically kills ciliated epithelial cells. B. pertussis peptidoglycan structure components, identified by high performance liquid chromatography and fast atom bombardment mass spectrometry change during virulent to avirulent phase transition (vir locus determinant) and in response to environmental conditions (mod locus determinant). The effects of vir and mod on the activity of peptidoglycan synthetic and degradative enzymes will be determined, elucidating for the first time how a two-component regulatory system is linked to peptidoglycan metabolism.